The present invention relates to flash memory technologies, and more specifically, to end of life testing.
Performance degradation over time is a critical issue with regard to flash-based solid state drive (SSD) technologies and, for that matter, all flash devices. These flash devices may be on peripheral component interconnect (PCI) cards, for example. Flash devices have memory organized as pages within blocks. While memory is programmed at a page boundary, an erase of memory occurs at the block boundary. This so-called program-erase cycle repeated over time causes degradation of the device. A controller, which may be implemented by an embedded processor, for example, must implement recovery functions such as error correction, bad block mapping, and wear leveling to mitigate issues created by the degradation over time. For example, the controller may retire bad blocks and replace them with reserve blocks.
Testing flash devices to simulate the control (e.g., replacement of bad blocks with reserve blocks) of device lifetime is an important aspect of ensuring accurate rating and reliability of systems that use SSD technologies or any flash devices. For example, an SSD vendor may specify that an SSD may be fully written ten times a day for up to five years. In order to set such an expectation, the vendor must perform lifetime testing of the device and ensure that the controller recovery mechanism is assured for the stated lifetime.